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本文利用文〔１〕中给出的不等式：ｃｔｇＡ＋ｃｔｇＢ＋ｃｔｇＣ≥２Ｒｒ－１，（１）（式中Ｒ、ｒ分别为△ＡＢＣ的外接圆和内切圆的半径，等号成立当且仅当△ＡＢＣ是正三角形）轻巧地导出了Ｗｅｉｓｎｂｏｃｋ不等式和Ｋｏｏｉｓｔｒａ不等式的新的下界．定理１若△Ａ...
This article uses the inequality given in [1]: ctgA + ctgB + ctgC ≥ 2Rr-1, (1) where R and r are the radius of the circumcircle and the inscribed circle of △ABC respectively, and the equal sign holds if and only if △ABC Is an equilateral triangle. We have deduced the new lower bounds of Weisnock inequality and Kooistra inequality. Theorem 1 if △A...